Derrick Salmon
New member
I have searched the forums but see no similar issues, so apologies if I have missed relevant posts. I have spent 3 days attempting to plot filled wind speed contours over plotted with streamlines for a regional domain using a wrfout file and, after MANY variations, I keep failing. I can get a plot but always with a global world view.
If anyone can suggest corrections to the script, or better, has an appropriate NCL script they would be good enough to share as a template this would be greatly appreciated.
typical failure message follows, and an early script version follows that.
(0) check_for_y_lat_coord: Warning: Data either does not contain
(0) a valid latitude coordinate array or doesn't contain one at all.
(0) A valid latitude coordinate array should have a 'units'
(0) attribute equal to one of the following values:
(0) 'degrees_north' 'degrees-north' 'degree_north' 'degrees north' 'degrees_N' 'Degrees_north' 'degree_N' 'degreeN' 'degreesN' 'deg north'
(0) check_for_lon_coord: Warning: Data either does not contain
(0) a valid longitude coordinate array or doesn't contain one at all.
(0) A valid longitude coordinate array should have a 'units'
(0) attribute equal to one of the following values:
(0) 'degrees_east' 'degrees-east' 'degree_east' 'degrees east' 'degrees_E' 'Degrees_east' 'degree_E' 'degreeE' 'degreesE' 'deg east'
; Load the required WRF NCL libraries
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
begin
; Open the WRF output file
filename = "wrfout_d02_2025-02-06_06:00:00" ; Modify with actual filename
f = addfile(filename, "r")
; Read U and V wind components at a specified level (e.g., 10m or a pressure level)
U10 = wrf_user_getvar(f, "U10", -1) ; 10m U-wind component
V10 = wrf_user_getvar(f, "V10", -1) ; 10m V-wind component
U10 = U10(0, :,
V10 = V10(0, :,
; Calculate wind speed
WSPD = sqrt(U10^2 + V10^2)
; Get lat/lon from file
lat = wrf_user_getvar(f, "XLAT", -1)
lon = wrf_user_getvar(f, "XLONG", -1)
lat = lat(0,:,
lon = lon(0,:,
; print(lat)
; print(lon)
; check XLAT and XLONG variables
printVarSummary(lat)
printVarSummary(lon)
; Open a workstation (X11 for interactive display, or change to PNG/PDF)
wks = gsn_open_wks("x11", "wind_speed_streamlines")
; Set contour plot resources
res = True
res@gsnMaximize = True
res@cnFillOn = True
res@cnFillPalette = "BlAqGrYeOrRe" ; Color map for wind speed
res@cnLinesOn = False
res@lbLabelBarOn = True
res@tiMainString = "Wind Speed (m/s) and Streamlines (10m)"
; Set streamline resources
st_res = True
st_res@gsnMaximize = True
st_res@stLineColor = "black" ; Streamlines in black
st_res@stMinDistanceF = 0.02 ; Controls streamline density
; covert WSPD from 3D to 2D
WSPD2 = WSPD(0,:,
; Generate the contour plot
plot = gsn_csm_contour_map(wks, WSPD2, res)
; Overlay streamlines
stream = gsn_csm_streamline(wks, U10, V10, st_res)
; Overlay streamlines on the contour plot
overlay(plot, stream)
; Draw and frame the plot
draw(plot)
frame(wks)
end
If anyone can suggest corrections to the script, or better, has an appropriate NCL script they would be good enough to share as a template this would be greatly appreciated.
typical failure message follows, and an early script version follows that.
(0) check_for_y_lat_coord: Warning: Data either does not contain
(0) a valid latitude coordinate array or doesn't contain one at all.
(0) A valid latitude coordinate array should have a 'units'
(0) attribute equal to one of the following values:
(0) 'degrees_north' 'degrees-north' 'degree_north' 'degrees north' 'degrees_N' 'Degrees_north' 'degree_N' 'degreeN' 'degreesN' 'deg north'
(0) check_for_lon_coord: Warning: Data either does not contain
(0) a valid longitude coordinate array or doesn't contain one at all.
(0) A valid longitude coordinate array should have a 'units'
(0) attribute equal to one of the following values:
(0) 'degrees_east' 'degrees-east' 'degree_east' 'degrees east' 'degrees_E' 'Degrees_east' 'degree_E' 'degreeE' 'degreesE' 'deg east'
; Load the required WRF NCL libraries
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
begin
; Open the WRF output file
filename = "wrfout_d02_2025-02-06_06:00:00" ; Modify with actual filename
f = addfile(filename, "r")
; Read U and V wind components at a specified level (e.g., 10m or a pressure level)
U10 = wrf_user_getvar(f, "U10", -1) ; 10m U-wind component
V10 = wrf_user_getvar(f, "V10", -1) ; 10m V-wind component
U10 = U10(0, :,
V10 = V10(0, :,
; Calculate wind speed
WSPD = sqrt(U10^2 + V10^2)
; Get lat/lon from file
lat = wrf_user_getvar(f, "XLAT", -1)
lon = wrf_user_getvar(f, "XLONG", -1)
lat = lat(0,:,
lon = lon(0,:,
; print(lat)
; print(lon)
; check XLAT and XLONG variables
printVarSummary(lat)
printVarSummary(lon)
; Open a workstation (X11 for interactive display, or change to PNG/PDF)
wks = gsn_open_wks("x11", "wind_speed_streamlines")
; Set contour plot resources
res = True
res@gsnMaximize = True
res@cnFillOn = True
res@cnFillPalette = "BlAqGrYeOrRe" ; Color map for wind speed
res@cnLinesOn = False
res@lbLabelBarOn = True
res@tiMainString = "Wind Speed (m/s) and Streamlines (10m)"
; Set streamline resources
st_res = True
st_res@gsnMaximize = True
st_res@stLineColor = "black" ; Streamlines in black
st_res@stMinDistanceF = 0.02 ; Controls streamline density
; covert WSPD from 3D to 2D
WSPD2 = WSPD(0,:,
; Generate the contour plot
plot = gsn_csm_contour_map(wks, WSPD2, res)
; Overlay streamlines
stream = gsn_csm_streamline(wks, U10, V10, st_res)
; Overlay streamlines on the contour plot
overlay(plot, stream)
; Draw and frame the plot
draw(plot)
frame(wks)
end
